PCI-e 4.0 and 3.0 "conversion"

[Adamator_Cz]

I just have the most peculiar question which it that, Can't technically 1x bandwidth of PCI-e 4.0 be converted into 2x PCI-e 3.0 ? Meaning if CPU has 20x PCI-e 4.0 lanes, can't it be that 16x PCI-e 4.0 would be used for GPU and the rest of bandwidth be converted into 8x PCI-e 3.0 on other slots?

 

Thanks for every response,

A.

[WereCat]

5 minutes ago, Adamator_Cz said:

I just have the most peculiar question which it that, Can't technically 1x bandwidth of PCI-e 4.0 be converted into 2x PCI-e 3.0 ? Meaning if CPU has 20x PCI-e 4.0 lanes, can't it be that 16x PCI-e 4.0 would be used for GPU and the rest of bandwidth be converted into 8x PCI-e 3.0 on other slots?

 

Thanks for every response,

A.

It should be possible but you need aditional hardware for that, it won't be done by your motherboard automatically.

So for example, if you have a PCI-e 3.0 x16 card running it PCI-e 4.0 x8 slot, the card will run at PCI-e 3.0 x8 speed, so you need some kind of extension card (there are some for NVME SSD) that also have some kind of controller to split the bandwidth. Not sure if there are any for the graphic cards.

[YoungBlade]

In theory, yes. I haven't heard of any consumer PCIe 4 devices or motherboards that support this, though, and I'm not sure if it will ever become common. The Liqid Honeybadger effectively does this. It takes 16 Gen 4 lanes and uses that bandwidth for 8x4 PCIe Gen 3 drives (32 lanes).

[Jurrunio]

This is pretty much what the PCH (chipset) partially does. Connection to CPU on one side, a lot of connections on the other, PCH handling all the traffic so everyone goes through fairly like a traffic intersection. It's just not necessarily the configuration you want.